Hi all,
however I've been noticing a huge difference in the way that plants grow in my RO plus GH+ minerals and my other tank which is just tap water. Limnobium reproduces easily, plants are healthy and thriving in the RO tank... while in the tap water tank plants are struggling. I'm sure you probably already know where the issues might be, probably again water chemistry.
I actually use a floating plant (and usually
Limnobium) as an indicator of nutrient deficiencies, this is mainly because you can discount CO2 shortage as a cause of any symptoms. I called it this method the <"
Duckweed Index">, partially because it was an alternative approach to <
"Estimative Index">, using Duckweed (
Lemna minor), and also because they were both methods that didn't require the tank owner to carry out any water testing.
I originally used
Lemna minor because it was the plant used in <"
water quality bio-assay">, but it is always yellow in soft water, even when there are high nutrient levels.
Limnobium has the advantage of growing over a large range of water hardness and nutrient levels, all that differs is the size and vigour of the plant.
Would the full water report from Affinity contain some clues regarding possible deficiencies or problems?
It would, but you can already make some informed guesses based on geology.
Your water is hard and the limestone and chalk aquifers in the UK are fairly pure CaCO3, it hasn't undergone <"
dolomotization and tends to have low magnesium levels">. Adding magnesium (Mg) is always a good idea. "Epsom Salts" (10% Mg) are an easily obtainable, and cheap, source. Hard water and high levels of calcium effect the uptake of iron, you need to add chelated iron. Have a look at <"
Duckweed Index says ....">.
Both magnesium and iron deficiencies cause yellow leaves (chlorosis), but if your new leaves are small and yellow? iron is the answer. Chlorosis in older leaves can be caused by more elements, the two most likely are nitrogen (N) and potassium (K), usually these are in reasonable amounts in SE England, but they may be deficient if your water comes from a very deep limestone aquifer. You can add them both via potassium nitrate (KNO3). After carbon (C) plants need most nitrogen and potassium, which is why <"
they can often limit plant growth">.
A final option is the third macro-nutrient phosphorus (P), but it is less likely to be in short supply. Magnesium and/or iron deficiency are the most likely options.
Really healthy Amazon Frogbit looks like
@Timon Vogelaar's in this thread <"
Do we really need...">.
cheers Darrel